Recently, a plasma CVD apparatus using a plasma enhanced chemical vapor deposition (PCVD) method is used to deposit a material such as silicon onto a substrate having a large area (for example, at least 1 m in length and at least 1 m in width). The plasma CVD apparatus is used for deposition processing of a film including amorphous silicon, microcrystalline silicon, silicon nitride and the like used for, for example, an amorphous solar cell, a microcrystalline solar cell, and a TFT (Thin Film Transistor) for a liquid crystal display, and has a function of cleaning a film adhered on a chamber or a discharge electrode by etching (self-cleaning).
As the discharge electrode of the plasma CVD apparatus, a discharge electrode including rod-like, longitudinal electrodes arranged approximately in parallel is often used, and such a discharge electrode is suitable for use in an very-high-frequency (30 MHz to 300 MHz) power supply to deposit a thin film onto a substrate having a large area (for example, refer to Patent Citation 1).    Patent Citation 1: Japanese Unexamined Patent Application, Publication No. 2005-113878